I read a doujin a little while back that I cannot find again for the life of me, but hey look a centaur thread!

The plot was featuring some kind of trainee vet/doctor who specialized in treating monster girls. His teacher was a different kind of Monster girl that he'd fucked in a previous chapter. Anyway, in this chapter a teenage centaur girl comes in and he has to masturbate her to help her, but ends up fucking her. Please tell me somebody has read this and knows what it's called, it was insanely hot and was what got me interested in horse girl pussy.